My wife is a professional potter. Where do I file the expenses for the equipment (kiln, wheel, etc.) materials (clay, glazes, etc.), rent for the studio she has?

[JulieCo]

You wife's business expenses will be filed on Schedule C along with her business income. 

To be brought to the Schedule C entry section, search for schedule c in the FIND field at the top of the screen and then select the Jump to link in the search results.  If income as already been added for this business, then select to EDIT the business and select to enter business expenses.